Measurements of multijet event isotropies using optimal transport with the ATLAS detector

A measurement of novel event shapes quantifying the isotropy of colliderevents is performed in 140 fb$^{-1}$ of proton-proton collisions with $\sqrts=13$ TeV centre-of-mass energy recorded with the ATLAS detector at CERN'sLarge Hadron Collider. These event shapes are defined as the Wassersteindistance between collider events and isotropic reference geometries. Thisdistance is evaluated by solving optimal transport problems, using the'Energy-Mover's Distance'. Isotropic references with cylindrical and circularsymmetries are studied, to probe the symmetries of interest at hadroncolliders. The novel event-shape observables defined in this way are infrared-and collinear-safe, have improved dynamic range and have greater sensitivity toisotropic radiation patterns than other event shapes. The measured event-shapevariables are corrected for detector effects, and presented in inclusive binsof jet multiplicity and the scalar sum of the two leading jets' transversemomenta. The measured distributions are provided as inputs to future MonteCarlo tuning campaigns and other studies probing fundamental properties of QCDand the production of hadronic final states up to the TeV-scale.